The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
Shaanxi Engineering Research Center of Edible and Medicated Fungi, School of Biological Science and Engineering, Shaanxi University of Technology, Hanzhong 723000, China.
J Biosci Bioeng. 2019 Jul;128(1):8-12. doi: 10.1016/j.jbiosc.2019.01.005. Epub 2019 Jan 30.
Bioproduction of organic acids under low pH condition without adding inducer and neutralizer is an economical craft to decrease downstream cost. Candida glycerinogenes had higher tolerances to low pH and lactic acid than Saccharomyces cerevisiae. QRT-PCR analysis showed that four of fifteen candidates functioned as potentially acid-inducible promoters in C. glycerinogenes. In particular, PCggmt1 showed the strongest induction ability at pH 2.5. Fluorescence analysis indicated that the induction ability of PCggmt1 gradually increased as the pH decreased. In addition, PCggmt1 had the binding sites of Msn2p/4p, Azf1p, and Nrg1p. PCggmt1 was further used to control the expression of lactate dehydrogenase gene from Rhizopus oryzae in C. glycerinogenes. Compared with pH 5.5, the specific activity of lactate dehydrogenase and lactic acid titer at pH 2.5 were increased by 229% and 218%, reaching 13.8 mU/mg and 12.3 g/L, respectively. These results presented here showed a potential to produce organic acid economically at low pH by the stress tolerant C. glycerinogenes and the novel low-pH inducible promoter PCggmt1.
在不添加诱导剂和中和剂的情况下，在低 pH 条件下进行有机酸的生物生产是降低下游成本的经济工艺。与酿酒酵母相比，甘油假丝酵母对低 pH 和乳酸具有更高的耐受性。QRT-PCR 分析显示，在 15 个候选基因中有 4 个在 C. glycerinogenes 中作为潜在的酸诱导启动子发挥作用。特别是，PCggmt1 在 pH 2.5 时表现出最强的诱导能力。荧光分析表明，随着 pH 值的降低，PCggmt1 的诱导能力逐渐增强。此外，PCggmt1 具有 Msn2p/4p、Azf1p 和 Nrg1p 的结合位点。进一步将 PCggmt1 用于控制来自米根霉的乳酸脱氢酶基因在 C. glycerinogenes 中的表达。与 pH 5.5 相比，在 pH 2.5 时，乳酸脱氢酶的比活和乳酸产量分别提高了 229%和 218%，达到 13.8 mU/mg 和 12.3 g/L。这些结果表明，通过具有应激耐受性的 C. glycerinogenes 和新型低 pH 诱导启动子 PCggmt1，可以在低 pH 条件下经济地生产有机酸。
